Alabama stand-off: how the FBI rescued Ethan

A tarpaulin covers the underground bunker where Ethan was held captive. Photo: Reuters

An Alabama man who held a five-year-old boy captive in an underground bunker for nearly a week engaged in a "firefight" with SWAT agents before he was killed during a rescue operation, the FBI says.

Special Agent Jason Pack said it appeared that 65-year-old Jimmy Lee Dykes also had "reinforced the bunker against any attempted entry by law enforcement".

Bomb technicians found two explosive devices on Tuesday on the property, he said. One was inside the bunker, and the other was located inside the plastic pipe through which he had been talking with negotiators.

Officers killed Mr Dykes on Monday, six days after he boarded a school bus, shot dead the driver and abducted the young boy.

The elite agents, from the FBI's Rescue Hostage Team, had been training for a number of possible scenarios in a mock-up bunker they had constructed near the property in Midland City where Mr Dykes was holding the young boy, named Ethan, hostage underground.

The FBI had inserted a high-tech camera into the bunker, allowing them to keep a constant watch on the 65-year-old Vietnam veteran, who harboured a deep distrust of government and was often seen patrolling his property with a gun.

But on Sunday evening, negotiations with Mr Dykes began to break down and Mr Dykes was seen through the covert camera holding a gun and acting increasingly agitated.

Authorities decided it was time to move.

At 3.12pm on Monday, the team of agents set off a "diversionary device", thought to be a flash-bang device to temporarily disorient Mr Dykes, before agents stormed through a door at the top of a bunker, NBC News reported.

The agents shot and killed Mr Dykes and rescued Ethan in an operation that took just minutes, CBS News reported.

Ethan, who suffers from Asperger's Syndrome and attention deficit-hyperactivity disorder, was not physically harmed during the daring mission and was recovering in hospital, where he was undergoing a number of tests.

Dale County Schools Superintendent Donny Bynum said the boy, who is due to celebrate his sixth birthday on Wednesday, was "running around the hospital room, putting sticky notes on everyone that was in there, eating a turkey sandwich and watching Spongebob".

A big party was also being planned to celebrate Ethan's sixth birthday, he said.

"We are still in the planning stages," Mr Bynum said.

"Our time frame is that we are waiting for Ethan, waiting on that process, but we are going to have it at a school facility, most likely the football stadium at Dale County High School."

He said many "tears of celebration" were shed Monday night when Ethan was reunited with his family.

It also has emerged that Ethan's mother hoped Mr Dykes would not be killed in the mission to save her son.

Alabama State Senator Harri Anne Smith told ABC News that Ethan's mother had asked police a few days ago not to kill Mr Dykes.

Ethan's mother had to be heavily sedated during the last days of the hostage ordeal as her anxiety levels and fear for her son rose.

Ethan's aunt Debra Cook told Good Morning America that Ethan had not yet told them anything about what he had seen in the the bunker, or how he had been snatched off his school bus. Mr Dykes, a retired trucker, had taken Ethan hostage on Tuesday last week after fatally shooting the bus driver Charles Albert Poland.

Ms Cook said the family was just overjoyed to have their "little buddy" back.

"He's a special child, 90 miles per hour all the time," Cook said. "[He's] a very, very loving child. When he walks in the room, he just lights it up."

Ethan's grandmother, Betty Jean Ransbottom, told Associated Press that she feared the ordeal could stay with the boy for the rest of his life.

"We know he's OK physically, but we don't know how he is mentally," she said.

The FBI continued to sweep the 100-acre property for explosives on Tuesday as part of an investigation so painstaking that authorities had not yet removed the body of the abductor, officials said.